After being optioned to Triple-A Norfolk prior to Tuesday’s game in Toronto, 22-year-old outfielder Xavier Avery became the latest in a long list of candidates to fall short in stabilizing the Orioles’ leadoff spot over the last two seasons.

Since second baseman Brian Roberts exited a game with concussion-related symptoms on May 16, 2011, the Orioles have been without a bona fide hitter at the top of the order despite trying a number of candidates in the role.

Shortstop J.J. Hardy had a higher degree of success than others last season, but his .295 on-base percentage while batting in the leadoff spot — to go along with a career .320 on-base percentage — didn’t exactly scream top-of-the-order hitter. In fact, Hardy’s power numbers (40 home runs in 176 games with the Orioles) suggest a player better suited to hit in the middle of the order than at the top.

This season, left fielder Nolan Reimold appeared to be an intriguing — but unconventional — choice with his career .338 on-base percentage, but a herniated disc in his neck has sidelined him after a fast start. In his absence, the combination of Endy Chavez, Robert Andino, Ryan Flaherty, and Avery has not been able to produce and set the table for the middle of the order.

Avery shows promise for the future, but his extended audition exposed the need for him to improve against off-speed pitches and develop further at Norfolk before he’s ready to assume the leadoff role on a permanent basis.

In 2011, the No. 1 spot in the order accounted for a .240 batting average and a .290 on-base percentage, the worst figures of any spot in the batting order. The numbers have been even worse this season as the top spot in the order has produced an anemic .213 average to go along with a .258 on-base percentage.

While many place too much emphasis on the batting order, the leadoff spot is expected to be occupied by a player with a strong ability to get on base and speed — a combination that has eluded the Orioles.

So, who might manager Buck Showalter turn to?

Ironically, it might be the man the Orioles have been trying to replace for over a year.

Five games into his minor league rehabilitation assignment, Roberts has yet to experience any setbacks while collecting two hits and two walks in 12 plate appearances at Double-A Bowie. Even if his rehab stint goes off without a hitch, it would be ambitious to expect Roberts to return to the form of a career .353 on-base hitter, but the 34-year-old infielder would easily become the most viable option in the top spot if he’s even remotely close to the player he was prior to the injury.

The debate will continue over how Showalter should handle Roberts’ workload and what it means for current second baseman Robert Andino, but the Orioles desperately need more production from the leadoff spot.

And with Roberts’ return looking more realistic every day, he would be as close to the ideal candidate as the Orioles have had since his exit over a year ago.

Starting pitching woes

The news of veteran pitcher Roy Oswalt signing a one-year deal with the Texas Rangers stole some of the thunder of this topic, but it’s become clear the Orioles need better starting pitching if they hope to maintain anything close to the 29-20 pace that’s put them in first place for much of the first two months of the season.

The current 4.31 earned run average from the starting rotation is just above the league average of 4.30, but that number becomes more concerning when you consider starters pitched to a 3.63 ERA in April but have posted a 4.94 mark so far in May.

Left-hander Zach Britton is expected to take the place of the struggling Tommy Hunter, who was optioned to Triple-A Norfolk on Tuesday with his ERA ballooning to 5.59 after another poor start in Toronto on Monday. However, the in-house options are few and far between after that, making the idea of Oswalt so appealing before he decided to sign with the defending American League champions.

The Orioles have few pieces in their system to warrant anything better than what they already have in making a trade, meaning they will likely have no choice but to depend on the continued success of Jason Hammel and Wei-Yin Chen and hope for more consistency from Jake Arrieta and Brian Matusz to prevent too much wear and tear on the bullpen.

While the health of Britton’s left shoulder remains the priority over any short-term results, the Orioles can only hope the 24-year-old more closely resembles the pitcher who was 5-2 with a 2.35 ERA in his first 10 starts last season than the one posting a 6.25 mark over his final 18 starts, which included a demotion and a trip to the disabled list with that sore shoulder.

With two days off during the current nine-game road trip, the Orioles will not need a fifth starter again until June 9. Barring any setbacks, Britton should be ready to join the starting rotation by that point in time.

Given Oswalt’s preference to play for a winner, Baltimore was an extreme long-shot, but his veteran presence for one season — without a long-term financial commitment — would have brought some much-needed stability and a veteran presence to the rotation.

Carrying Flaherty becoming burdensome?

Showalter has said how impressed he is with Rule 5 selection Ryan Flaherty on several occasions this season, but you have to wonder if the 25-year-old is becoming too great a burden on the 25-man roster for a first-place team.

Injuries provided the utility player more playing time in the early stages of May, but his .143 batting average (7-for-49) has led to less playing time over the last two weeks. Since going 0-for-4 in Kansas City on May 17, Flaherty has received only one start and four plate appearances while being relegated to the bench.

The idea of a Rule 5 player on a team projected to be in last place sounds like an acceptable situation, but carrying a player like Flaherty when you’re trying to win is a dicey proposition, especially when the Orioles have elected to go with a three-man bench and 13 pitchers at times when the bullpen has been overworked.

In addition to Flaherty, infielder Steve Tolleson doesn’t have a strong hold on his roster spot, so it will be interesting to see what executive vice president of baseball operations Dan Duquette decides to do if and when Roberts is ready to be activated on June 12. Regardless of whether Roberts takes Andino’s starting job or not, his addition will take away another roster spot and make you wonder if the Orioles can keep Flaherty around much longer if he isn’t going to produce.